SNLA437A December 2023 – October 2025 DP83822H , DP83822HF , DP83822I , DP83822IF , DP83826I
If applicable, Serial Management Interface can be useful in providing valuable status fields during a debug. However, verify that this communication is accurate to avoid compounding issues. MDIO should pull up to the VDDIO with a 2.2kΩ pullup resistor. Probe MDIO to confirm the default voltage.
Attempt to write and read the registers. Verify the MDIO data sequence with the data sheet to make sure the MDIO read access timing is correct.
| SMI Protocol | <idle><start><op code><device addr><reg addr><turnaround><data><idle> |
|---|---|
| Read Register | <idle><01><10><AAAAA><RRRRR><Z0><XXXX XXXX XXXX XXXX><idle> |
| Write Register | <idle><01><01><AAAAA><RRRRR><10><XXXX XXXX XXXX XXXX><idle> |
Figure 2-6 MDC/MDIO Write Example
Figure 2-7 MDC/MDIO Read Example